This invention relates to stripping solutions for removing polymeric organic materials coated onto various metal, metal oxide, glass or insoluble polymeric substrate surfaces and provides organic mixtures comprised of sulfonic acids, hydrocarbons and sulfones, constituted in such a way to be compatible with aluminum and semiconductor manufacture. Specifically, this invention provides a sulfonic acid-hydrocarbon based stripping solution that will not generate brown stains on aluminum substrate during semiconductor processing of substrate aluminum.
During manufacture of semiconductors and semiconductor microcircuits, it is frequently necessary to coat the materials from which the semiconductors and microcircuits are manufactured with a polymeric organic substance, generally referred to as a photoresist, e.g., a substance which forms an etch resist upon exposure to light. These photoresists are used to protect selected areas of the surface of the sustrate, e.g., silicon, SiO.sub.2 or aluminum, from the action of the etchant while such etchant selectively attacks the unprotected area of the substrate. Following completion of the etching operation and washing away of the residual etchant, it is necessary that the resist be removed from the protective surface to permit essential finishing operations.
A common method used in removing the photoresist from the substrate is by contacting the substrate with an organic stripper. These organic strippers in the past have been composed of various components whose purpose it was to lift and remove the polymeric photoresist from the substrate and usually contained phenol or phenol compounds and chlorinated hydrocarbon compounds. The use of phenol or phenol compounds or chlorinated hydrocarbon compounds results in a distinct disadvantage due to the toxicity of phenol as well as the pollution problems arising from the disposal of phenol or phenol compounds such as cresols, phenol sulfonic acid and the like or the disposal of chlorinated hydrocarbon compounds. U.S. Pat. No. 4,165,294 discloses stripping solutions that are phenol-free and chlorinated hydrocarbon-free and that are water rinsable.
The stripping solutions of U.S. Pat. No. 4,165,294 while performing effectively have been found to have the drawbacks of generating brown stains during processing, particularly on aluminum substrates, used in semiconductor elements. Brown stains of this character are unsightly and in some cases affect performance. Both of these drawbacks are undesireable. It is accordingly indicated that a need exists for a phenol-free and chlorinated hydrocarbon-free stripping solution which in use do not evidence a brown stain of the semiconductor substrate.